1. Field of the Invention
The present invention relates to differential assemblies for vehicles such as automobiles.
2. Background Infomation
Automobiles include differential assemblies to compensate for different wheel speeds when the vehicle moves in a non-linear path. For example, when an automobile is turning to the left or right, the radially inward wheels rotate at a speed that is lower than the speed of the outer wheels. The differential assembly allows different rotational speeds of the drive wheels when the vehicle is in a turn.
There have been developed various types of differential member assemblies including a product sold by Vehicular Technologies, Inc. of Costa Mesa, California under the trademark "Performance Locker" for improving traction. The Performance Locker automatic positive-locking differential fits within a differential case and couples to the drive axles of the vehicle, the differential case having a ring member fastened thereto driven in rotation by a pinion member on the drive shaft of the vehicle. The Performance Locker differential includes a pair of drive members that engage a pair of coupler members through facing, inclined teeth. The coupler members are attached to the wheel axles. The drive members are coupled for rotation by the differential case by the differential pinion pin. Rotation of the vehicle drive shaft is translated to the wheel axles through the ring gear, case, pinion pin, drive members and mating coupler members.
The pinion pin loosely fits within a pair of grooves in the side of each drive member opposite the inclined teeth. The grooves have inclined sides, with a width that is greater than the diameter of the pinion pin. When the vehicle is being powered or braked by the vehicle engine, the pinion pin will be rotated about an axis perpendicular to the axis of the pinion pin to engage and drive one, or both (particularly when the drive wheels of the vehicle are on a slippery or soft surface) drive members to transfer the torque of the drive member to the respective coupler member. When the vehicle proceeds around a curve, one of the drive wheels rotates at a different speed than the other wheel. The different speed initially causes the drive member associated with the faster wheel, if the engine is powering the vehicle, or the slower wheel if the engine is retarding the vehicle, to rotate away from contact with the pinion pin. This allows the drive member to move axially away from the respective coupler member if so encouraged.
The drive and coupler members each have inclined teeth on the adjacent faces thereof. When the edges of the grooves in a drive member move away from the pinion pin within the limit of rotation of one drive member with respect to the other drive member, the drive member teeth climb and slide over the respective coupler member teeth so that the wheels can rotate at different speeds. Springs in the assembly bias each drive member into full engagement with the respective coupler member when the teeth on the drive member and coupler member realign.
In some differential assemblies, particularly for high ring gear/pinion gear ratios, the pinion pin cannot be removed with the ring gear in position because of interference of the ring gear teeth with the pinion pin axial movement. By way of example, the pinion pin in the Ford 7.5 inch (ring gear diameter) can be shifted axially so as to allow removal of the C clip holding the axle in position for axle removal, but the pinion pin cannot be fully removed without disassembly of the differential case bearing caps and then removal of the ring gear from the case. This in turn requires a skilled mechanic to re-setup the ring and pinion gear adjustment. Even once this is done, however, whether for installation and service of a locking differential, a conventional or a limited slip differential, it would be advantageous to be able to again service and/or replace cluster gears of a conventional differential, drive and coupler members of a locking differential, etc without having to repeat the entire differential disassembly and reassembly and gear setup process.